Several transmission schemes for automatic transmissions with a non-shiftable series assembly and a shiftable main gearset have become known in U.S. Pat. No. 5,106,352 A in which a total of six forward gears are shiftable without group shifting. The main gearset here is constructed as a two webbed four shafted transmission with two coupled planetary gearsets. The non-shiftable series assembly can be constructed as a single web planetary operation or as a two shafted transmission with two fixed spur gear pairs.
If the series assembly is constructed as a non-shiftable single web planetary transmission, then U.S. Pat. No. 5,106,352 A suggests connecting the input shaft of the automatic transmission fast with this single web planetary transmission and to transmit selectively the torque thus generated in the series assembly through various shift elements to gearset components of the main gearset. Furthermore, the input shaft is connectable with the main gearset through a shifting element. If the series assembly is constructed as a two shaft transmission with constant spur gear stages, U.S. Pat. No. 5,106,352 A suggests connecting the input shaft fast with one spur gear each of two spur gear pairs. Input shaft and output shaft of the automatic transmission are thus not coaxial in relation to each other. Two rotational speeds are generated by these two spur gear pairs that are transmittable through various shifting elements to gearset components of the main gearset.
In the older German patent application P 199 49 507.4 of the applicant, several transmission schemas for an automatic multi-speed transmission with various combinations of planetary gearsets are described. By suitable connection of a non-shiftable planetary gearset combination in a series assembly to a shiftable planetary gearset combination in a distribution side assembly, at least seven forward gears can be respectively shifted without group shifting. The number of shiftable forward gears is moreover at least twice as large as the number of shifting elements. Series assembly and distribution side assembly are constantly arranged coaxially in relation to each other.
DE-P 199 49 507.4 also suggests constructing the distribution side assembly as two webbed four shaft transmissions. Here an arrangement of two individual mechanically coupled single web planetary gearsets is to be understood by two webbed four shafted transmission in which the coupled unit has four so-called “free shafts” as a consequence of a twofold component connection, whereby a “shaft” can be a sun gear, a hollow gear or even a web of a planetary set.
The object of the present invention now consists in that, proceeding from the state of the art mentioned, to develop a multi-speed transmission with non-coaxial arrangement and at least seven forward gears shiftable without group shifting with respect to building space, with low building expenditure, favorable gear gradation and great spread.